title: Self-assembled molecular platforms for bacteria/material biointerface studies: importance to control functional group accessibility.
abstract: Highly controlled mixed molecular layers are crucial to study the role of material surface chemistry in biointerfaces, such as bacteria and subsequent biofilms interacting with biomaterials. Silanes with non-nucleophilic functional groups are promising to form self-assembled monolayers (SAMs) due to their low sensitivity to side-reactions. Nevertheless, the real control of surface chemistry, layer structure, and organization has not been determined. Here, we report a comprehensive synthesis and analysis of undecyltrichlorosilane- and 11-bromoundecyltrichlorosilane-based mixed SAMs on silicon substrates. The impact of the experimental conditions on the control of surface chemistry, layer structure, and organization was investigated by combining survey and high-resolution X-ray photoelectron spectroscopy analysis, wettability measurements, and ellipsometry. The most appropriate conditions were first determined for elaborating highly reproducible, but easily made, pure 11-bromoundecyltrichlorosilane SAMs. We have demonstrated that the control is maintained on more complex surfaces, i.e., surfaces revealing various chemical densities, which were obtained with different ratios of undecyltrichlorosilane and 11-bromoundecyltrichlorosilane. The control is also maintained after bromine to amine group conversion via SN2 bromine-to-azide reactions. The appropriateness of such highly controlled amino- and methyl-group revealing platforms (NH2-X%/CH3) for biointerface studies was shown by the higher reproducibility of bacterial adhesion on NH2-100%/CH3 SAMs compared to bacterial adhesion on molecular layers of overall similar surface chemistry but less control at the molecular scale.
authors.affiliation: Institut of Materials Science of Mulhouse (CNRS UMR7361), Mulhouse, France.
authors.forename: Judith
authors.initials: J
authors.lastname: Böhmler
authors.forename: Arnaud
authors.initials: A
authors.lastname: Ponche
authors.forename: Karine
authors.initials: K
authors.lastname: Anselme
authors.forename: Lydie
authors.initials: L
authors.lastname: Ploux
mesh_terms: D000327:Adsorption; D001386:Azides / Q000737:chemistry; D001419:Bacteria / Q000737:chemistry*; D001422:Bacterial Adhesion; D001672:Biocompatible Materials / Q000737:chemistry*; D018441:Biofilms; D001966:Bromine / Q000737:chemistry; D012825:Silicon / Q000737:chemistry; D013499:Surface Properties
chemical_list: D001386:Azides; D001672:Biocompatible Materials; D001966:Bromine; D012825:Silicon